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In-Reply-To: <ae74bb79-a68e-a319-f61c-5b93fd70ae59@gmail.com>
From: "Ard Biesheuvel" <ard.biesheuvel@linaro.org>
Date: Wed, 30 Oct 2019 08:12:57 +0100
Message-ID: <CAKv+Gu8oUfSfMLW17QOwBCrrn+3AggHND6b0KZWfB=Npo9d8Hw@mail.gmail.com>
Subject: Re: [edk2-devel] How /sys/firmware/fdt getting created
To: Prabhakar Kushwaha <prabhakar.pkin@gmail.com>
Cc: edk2-devel-groups-io <devel@edk2.groups.io>
Content-Type: text/plain; charset="UTF-8"

On Tue, 29 Oct 2019 at 18:17, Prabhakar Kushwaha
<prabhakar.pkin@gmail.com> wrote:
>
> Hi All,
>
> I am working on Ubuntu-18.04 with UEFI on ARM64(64 bit) platform. The
> UEFI used is having ACPI tables.
>
> I am trying to understand where and how /sys/firmware/fdt is getting
> created. is it created by UEFI or grub and passed to Linux?
>

Neither. It is created by Linux itself.



> below is the dts format of /sys/firmware/fdt.
>
> /dts-v1/;
>
> / {
>
>         chosen {
>                 linux,uefi-mmap-desc-ver = <0x1>;
>                 linux,uefi-mmap-desc-size = <0x30>;
>                 linux,uefi-mmap-size = <0xcc0>;
>                 linux,uefi-mmap-start = <0x0 0xeda13018>;
>                 linux,uefi-system-table = <0x0 0xfafd0018>;
>                 bootargs = "BOOT_IMAGE=/boot/vmlinuz-5.4.0-rc4+
> root=UUID=798a858c-4f20-4b99-aa40-99bff9394093 ro crashkernel=2G
> console=ttyAMA0";
>                 linux,initrd-end = <0x0 0xeb381a34>;
>                 linux,initrd-start = <0x0 0xdd5f5000>;
>         };
> };
>
> also, under what scenario/config fields is getting added fdt.
>         #size-cells = <0x02>;
>         #address-cells = <0x02>;
>
> --prabhakar (pk)
>
> 
>